Two days after exchanging harsh warnings with Iranian leaders, U.S. President Donald Trump says he is still eager to negotiate a new nuclear deal with Tehran.

"We'll see what happens, but we're ready to make a real deal, not the deal that was done by the previous administration, which was a disaster," Trump said on July 24 in a speech to veterans in the U.S. state of Missouri.

Trump over the weekend had threatened Tehran with "consequences the likes of which few throughout history have ever suffered before" after Iranian President Hassan Rohani had warned Trump not to "play with the lion's tail."

The exchange of harsh rhetoric was reminiscent of the threats that volleyed back and forth between Trump and North Korean leader Kim Jong Un last year -- exchanges that disappeared after the two adversaries agreed to negotiate a nuclear deal at a summit this spring.

U.S. Defense Secretary Jim Mattis on July 24 declined to comment directly on Trump's threats against Iran, but he voiced his own concerns about Iranian actions in the Middle East, including Tehran's support for Syrian President Bashar al-Assad and for Huthi rebels fighting the government in Yemen.

"I think the president was making very clear that they're on the wrong track," Mattis said on a visit to California.

"It's time for Iran to shape up and show responsibility as a responsible nation. It cannot continue to show irresponsibility as a revolutionary organization that is intent on exporting terrorism, exporting disruption, across the region."